The purpose of the project is to gain insight into the biologic function of the platelet membrane and the structure/function relationship within the membrane. The eventual aim is to use this information pharmacologically to modify platelet response in disease states such as atherosclerosis, (strokes & heart attacks), and thromboembolic arterial disease. Adhesion is the initial platelet response to endothelial injury, yet it is the least-well studied of platelet functions. To date, we have successfully set up an adhesion assay for a biologic surface and are testing the requirements for adhesion. So far we have found that Ca is absolutely required and that albumin and fibrinogen are not required. We are studying the mapping and association of platelet membrane functions with defined chemical groups in the platelet membrane. So far we have found specific association between sulfhydryl groups and aggregation, 5HT uptake, and the release reaction; between carboxyl groups and the thrombin receptor for release, the collagen receptor site, aggregation and 5HT uptake; bwtween amino groups and 5HT uptake. In studies on components of the primary hemostatic plug, we have found that both platelets and fibrin add to the tensile strength observed. The use of platelets, fibrinogen, and thrombin to seal injuries to the anterior chamber of the rabbit eye significantly improves the chances for reestablishing intraocular pressure and saving the eye. The use of fibrinogen and thrombin alone did not work as well. BIBLIOGRAPHIC REFERENCES: Pearl, M., Wustrack, K.O., Harbury, C.B., Rubenstein, E., and Kaplan, E.N.: Microvascular anastomosis using a blood product sealant-adhesive. Surgery, Gynecology and Obstetrics. 44: 227-231, 1977. Silverberg, G., Harbury, C.B., and Rubenstein, E.: A physiologic sealant of cerebrospinal fluid leaks. J. Neurosurg. 46: 215-219, 1977.